The Leafhopper Genus Giprus (Homoptera: Cicadellidae)
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AN ABSTRACT OF THE THESIS OF JANE ROSAMUND SAWBRIDGE for the MASTER OF SCIENCE (Name of Student) (Degree) in ENTOMOLOGY presented on q 7'2.1 (Major) (Date) Title: THE LEAFHOPPER GENUS GIPRUS (HOMOPTERA:CICADELLIDAE) Redacted for privacy Abstract approved: Paul Oman Members of the deltocephaline leafhopper genus Giprus Oman live on grasses, primarily in the desert - scrub, chaparral, and marine sand dune communities of western North America.Of 16 known species, 10 are undescribed.Recharacterization of the genus results in exclusion of Laevicephalus incongruus Oman.Differen- tiation of species is primarily dependent on male genital structures; characterization of species is through illustration, verbal description, and a diagnostic key.Infraspecific variation noted is primarily of two types:size and color variation in two dune- inhabiting species, and variation in shape and size of accessory aedeagal processes of G. siskiyou (Oman). The fifth instar nymph of Giprus is characterized. It is concluded that the distributional patterns of the Oregon Species of Giprus are not determined by host associations. The Leafhopper Genus Giprus (Hornoptera:Cicadellidae) by Jane Rosamund Sawbridge A THESIS submitted to Oregon State University in partial fulfillment of the requirements for the degree of Master of Science June 1972 APPROVED: Redacted for privacy Professor of Entomology in charge of major Redacted for privacy Head of Department of Entomology Redacted for privacy Dean of Graduate School Date thesis is presented )61,11 2 Q, Typed by Opal Grossnicklaus for JANE ROSAMUND SAWBRIDGE ACKNOWLEDGEMENTS I am grateful to the following people for their contributions to this project: Dr. Paul Oman for suggesting the project, collecting specimens, and offering advice and constructive criticism throughout the study; Dr. John D. Lattin, Dr. Kenton L. Chambers, and David F. Sawbridge for, reviewing the manuscript; Mrs. La Rea Johnston of identifying many of the plants collected; and Chandra A. Viraktamath for collecting specimens.I would also like to thank the Entomology Department, Oregon State University, for funding a field trip to Nevada, Utah, and southern California. This study was supported in part by Grants GB-7706 and GB-28292 "Phylogeny and Distribution of Nearctic and Palearctic Leafhoppers," from the National Science Foundation to Dr. Paul Oman. TABLE OF CONTENTS INTRODUCTION 1 MATERIALS AND METHODS GENERIC CHARACTERISTICS 9 RELATIONSHIP TO OTHER GENERA 11 MORPHOLOGICAL DIFFERENTIATION AND COMPARISON OF SPECIES 13 INFRASPECIFIC VARIATION 20 KEY TO SPECIES 29 DESCRIPTIONS OF SPECIES 33 DISTRIBUTION, HABITAT, AND HOST PLANTS 51 LIFE CYCLE 64 PHYLOGENY WITHIN GIPRUS 68 FUTURE AREAS OF RESEARCH 72 ILLUSTRATIONS 73 BIBLIOGRAPHY 85 APPENDIX 88 INDEX TO GENERA AND SPECIES 89 LIST OF FIGURES Figure Page 1. Ratio of head width (W) to head length (L) for all species of Giprus 19 2. Lengths of Giprus W and Giprus P. 22 2a. Mean length of Giprus W at 4.0 km N Waldport 1967-1971. 22 2b. Mean length of Giprus W at each site in 1971. 22 2c. Mean length of Giprus P at each site in 1971. 22 3. Species groups of Giprus based on the structure of the male genitalia. 69 Giprus siskiyou : forewing 77 5 Giprus M :fifth instar nymph 77 6 Giprus siskiyou : head 77 7 Giprus W : head 77 8 Giprus C : female 7th sternum 78 9 Giprus cinerosus: female 7th sternum 78 10 Giprus R : female 7th sternum 78 11 Giprus T : female 7th sternum 78 12 Giprus S : female 7th sternum 78 13 Giprus joaquinus : female 7th sternum 78 14 Giprus M : female 7th sternum 78 15 Giprus angelus: female 7th sternum 78 16 Giprus V :female 7th sternum 78 Figure Page 17 Giprus pacificus : female 7th sternum 78 18 Giprus W ; female 7th sternum 79 19 Giprus G ; female 7th sternum 79 20 Giprus P ; female 7th sternum 79 21 Giprus siskiyou : female 7th sternum 79 22 Giprus cartwrighti : female 7th sternum 79 23 Giprus siskiyou. ; male genital capsule 79 24 Giprus W : male genital capsule 79 25 Giprus R :male genital capsule 79 26 Giprus V : male genital capsule 79 27 Giprus cartwrighti : male genital capsule 79 28 Giprus cinerosus : connective and aedeagus 80 29 Laevicephalus sylvestris (Osborn & Ball) connective and aedeagus 80 30 Laevicephalus incongruus :connective, style, and aedeagus 80 31 Giprus siskiyou (Mt. Shasta, California) : connective, style, and aedeagus 80 32 Giprus siskiyou (15 miles NE Alturas, California): connective, style, and aedeagus 81 33 Giprus siskiyou (Cliffdell, Washington): connective, style and aedeagus 81 34 Giprus siskiyou (11 miles E Frenchglen, Oregon) ; connective, style, and aedeagus 81 35 Giprus W : connective, style, and aedeagus 81 Figure Page 37 Giprus joaquinus : connective, style, and aedeagus 81 38 Giprus D : connective, style, and aedeagus 82 39 Giprus angelus: connective, style, and aedeagus 82 40 Giprus V : connective, style, and aedeagus 82 41 Giprus P : connective, style, and aedeagus 82 42 Giprus M : connective, style, and aedeagus 82 43 Giprus S : connective, style, and aedeagus 82 44 Giprus T (Tehachapi Pass, California) : connective, style, and aedeagus 83 45 Giprus T (Mill Valley, California)connective, style, and aedeagus 83 46 Giprus pacificus : connective, style, and aedeagus 83 47 Giprus C : connective, style, and aedeagus 83 48 Giprus R : connective, style, and aedeagus 83 49 Giprus cinerosus : connective, style, and aedeagus 83 50 Giprus cartwrighticonnective, style, and aedeagus 83 51-67 Giprus siskiyou (3 miles S Weed, California) : apex of aedeagus 84 68-87 Giprus siskiyou (36 miles E Klamath Falls,' Oregon ): apdx of iaedeagus 84 LIST OF TABLES Table Page 1. Summary of length data for all species of Giprus 21 Climatic data for recording stations closest to collecting sites of Giprus V, Giprus M and G. siskiyou 56 3. Climatic data for selected Pacific Coast recording stations. 60 4. Dates of collettion of Giprus W at Waldport (all years). 65 5. Collection of Giprus by week. 66 THE LEAFHOPPER GENUS GIPRUS (HOMOPTERA:CICADELLIDAE) INTRODUCTION Members of the genus Giprus Oman are slender, small to medium-sized leafhoppers, cinereous to amber in color, and fre- quently with blackish-brown markings on the wings and head.They inhabit western North America, occurring in climatic zones ranging from coastal to continental at latitudes from 32°N to 47°N at eleva- tions from sea level to 1981 m.The genus is associated with various species of grasses, usually in chaparral, desert scrub, or sagebrush communities.Giprus is placed in the Subfamily Deltocephalinae, Tribe Deltocephalini.It is a member of that group of deltocephaline leafhoppers characterized by a linear connective and an articulation between the connective and the aedeagus and is closely related to several other grassland genera (Laevicephalus De Long, Lemellus Oman, Sorhoanus Ribaut, Verdanus Oman, and Cazenus Oman). This study summarizes present knowledge of the taxonomy, distribution, biology, and ecology of Giprus.It identifies areas where further study is needed in order to understand the phylogeny of the group and the factors responsible for the evolution of a large number of species in a relatively small geographic area. Taxonomic literature dealing with members of the genus Giprus 2 provides an excellent illustration of the gradual restriction of generic concepts in the Cicadellidae which has occurred in the past half cen- tury.The first known species was described by Van Duzee (1892) as Deltocephalus cinerosus. At that time, the genus Deltocephalus Burmeister was a large, poorly defined group containing many diverse elements. De Long (1926), recognizing the need to divide Deltocephalus into compact, more easily definable groups, erected a number of subgenera.The subgenus Laevicephalus, in which D. cinerosus was placed, was distinguished by its wing venation, color, curvature of the vertex, and the angle of the vertex and the front.When Laevicephalus was elevated to generic status in 1929 by De Long and Sleesman, it was noted that the genus contained spe- cies with a great diversity of genitalic structures.In 1937 Oman recognized and characterized, primarily on the basis of the male genitalia, a "cinerosus group" of Laevicephalus which included L. cinerosus and five additional species:L. angelus Oman, L. pacificus Oman, L. joaquinus Oman, L. siskiyou Oman, and L. incongruus Oman.In 1949 Oman removed the "cinerosus group" and L. cart - wrightir which he had described in 1932, from Laevicephalus and erected the genus Giprus to contain them. Although no significant contributions to our knowledge of Giprus have been made since 1949, numerous studies of the leafhopper fauna of the grasslands of Europe and Asia by Emelt yanov (1964) and others 3 have produced no evidence that Giprus occurs outside the Nearctic region.The discovery of what appeared to be a series of new species of Giprus in 1968-69 led to renewed interest in the genus.The ques- tions arose as to whether the previously held concept of species as applied to Giprus was too narrow and as to whether these new forms were discrete species or extreme infraspecific variantsof other species.This study was undertaken in order to gain a better under- standing of the circumscription of species in Giprus and in part involved a study of infraspecific variation to determine the range of variation that could be expected within a population.An attempt was also made to determine the factors responsiblefor the appar- ently limited distribution of some of the species.As preliminary investigations had suggested that different species of Giprus were collected from different species of grasses, it was initially postulated that the distribution of each species of Giprus might be dependent upon the distribution of the grass on which it fed,and that each spe- cies had a single grass species as host. 4 MATERIALS AND METHODS Over 3,000 specimens, including one holotype and 87 paratypes of seven species, were examined during the course of this study.